544 F. W. GAMBLE AND J. H. ASHWORTH. 



peristaltic movement, the septa have been reduced to the 

 narrow strip of connective tissue binding the segmental 

 vessels together. The three strong anterior " diaphragms/' 

 the loss of septa in the gastric region, and their reappear- 

 ance in the tail are important features which Arenicolidse, 

 Scalibregmidte, and Opheliidae have in common. The ne- 

 phridia of the three families agree in general form. In the 

 8calibregmida9 they have never, of recent years, been care- 

 fully examined, so that Danielssen's little-known account 

 of them may be worth quoting (' Anatomisk-physiologisk 

 Undersogelse af Scalibregma inflatum,' 1859, p. 69) : 

 '^ Along the inner side of the body-cavity, from the sixth 

 segment up to the anus, there is a row of obliquely placed 

 loop-like bodies. The external upper and smaller end is 

 placed on the inner side of a swelling near the ventral 

 parapodium, while the rounded inner or lower end hangs 

 free in the body-cavity at the sides of the ventral vessel. 

 From the sixth to the thirteenth segments, at the sides of 

 each segment, these looped bodies are placed so close together 

 that the more anterior ones seem to have grown together. 

 These six are the largest (four lines long). In the following 

 sixteen segments they become smaller as one goes back. 

 Altogether there are forty to forty-two on each side. Each 

 is composed of a fine sac-like membrane, ciliated internally. 

 They are crammed with large, round, clear cells and yellow- 

 green ' molecules,' which lie in a clear fluid. I found no 

 ducts to these organs, nor did I see developed eggs in them, 

 though the body-cavity fluid was full of eggs. Yet I believe 

 they were the ovaries." Further on Danielssen gives an 

 account of the testes which are present in addition to the 

 ovaries in these Scalibregma. In captivity the eggs are 

 discharged by rupture of the body-wall. 



This, we believe, is the only account of the nephridia of 

 this genus. For it is pretty certain that the sac-like bodies 

 which Danielssen thought were ovaries are the nephridia, 

 which, as he says, are ciliated internally, and therefore 

 presumably have a distinct nephrostome, while the yellow- 



